CN102031008B - Production method of thin prepreg with high-content filler adhesive system - Google Patents

Abstract

The invention relates to a production method of a thin prepreg with a high content of filler glue, comprising the following steps: Step 1, providing electronic-grade glass fiber flat cloth; the nominal mass per unit area of the electronic-grade glass fiber flat cloth is 15-50g /m ² , the gap area of the warp and weft yarns is 0-0.01mm ² ; step 2, prepare resin glue with high content of filler, wherein the weight percentage of filler is 15-60%; step 3, make electronic grade glass fiber flat cloth Impregnate the above-mentioned resin glue solution with high filler content and bake to prepare a thin prepreg with high filler glue content. The production method of the thin prepreg with a high-content filler glue system of the present invention can effectively solve the apparent pinhole defect of the thin prepreg, improve its qualification rate, ensure the electrical performance and reliability of the copper clad laminate made by using it, and then ensure the reliability of the PCB board. Electrical insulation performance, improve product quality.

Description

Production method of thin prepreg with high content of filler glue system

technical field

The invention relates to the field of copper clad laminates, in particular to a production method of a thin prepreg with a high content of filler glue system.

Background technique

Copper-clad laminates, as the basic material of printed circuit boards, are reinforced materials (such as electronic-grade glass fiber cloth) impregnated with resin (glue), which are baked into prepregs with a certain degree of curing, and then a One or more prepregs are stacked together according to certain structural requirements, and one or both sides are covered with copper foil, and a composite material is made by hot pressing.

In IPC4412, "Specifications for Handling E Glass Fiber Cloth for Printed Boards" clearly stipulates the type of glass fiber cloth. The types of glass fiber commonly used as reinforcing materials for electrical and electronic laminates are listed in the following table 1:

Table 1. Basic physical properties of commonly used electronic glass fiber cloth

Treated "E" fiberglass cloth for printed circuit boards is a plain weave fiber cloth in which each warp yarn passes over and under a weft yarn, and each weft yarn passes over a warp yarn. Pass the top and back warp yarns under, interlacing every other warp. It is made by twisting a certain number of single yarns according to different yarn numbers to form warp yarns and weft yarns, and then weaving warp yarns and weft yarns interlaced. The plain weave is a uniform checkerboard pattern, and the glass fiber cloth will form gaps between the intersection points of the warp and weft yarns, which are not covered by the glass yarn. In IPC-4412-2002, in the specification of "E" grade glass fiber glass cloth for printed circuit boards, there is no regulation on the width of warp and weft yarns, and no corresponding regulations on the requirements for the gap area between warp and weft yarns.

The utility model patent with the patent number of 201220995 discloses an electronic-grade glass fiber flat cloth, whose characteristics stipulate the width of each bundle of warp and weft yarns. Improvement, suitable for high-precision, high-performance copper-clad laminates; the utility model patent No. CN201220996 discloses an electronic-grade glass fiber ultra-thin cloth, whose characteristics define the width range of each bundle of warp and weft yarns, and the structure after the yarn bundles are loose more evenly. Compared with ordinary cloth, it can improve the appearance and bending resistance of copper clad laminates. The above two utility model patents on thin electronic glass fiber flat cloth do not involve the description of the void area of the warp and weft yarns of the glass cloth, nor do they indicate that the flat thin electronic fiber cloth is suitable for specific adhesive systems.

In recent years, the application of inorganic filler technology in copper clad laminates (CCL) has become an important topic in the technology development of this industry. The introduction of inorganic fillers in copper clad laminates can improve the mechanical properties, heat resistance, electrical properties, dimensional stability and other characteristics of the board. Therefore, more and more CCL products use inorganic fillers to improve one or more of the above properties. There are many types of fillers, and the inorganic fillers used in copper clad laminates generally include: aluminum hydroxide, silicon micropowder, talcum powder, kaolin, calcium carbonate, etc. Typical glue formulations used for copper clad laminates include: resins, curing agents, accelerators, solvents and fillers. According to the content of filler in the rubber system, it is divided into the following table 2:

Table 2. Classification of rubber systems with different weight content ratios of fillers

Phenolic resin is formed by polycondensation of phenolic compounds and aldehyde compounds. The Dicy curing agent traditionally used in the FR-4 adhesive formula has the advantages of good latent and adhesive properties, but has the disadvantages of strong hygroscopicity and poor heat resistance. It has become a current technical trend to choose novolac as the main curing agent of the resin system. It can improve the dimensional stability, moisture resistance and chemical resistance of the product, and it is also beneficial to improve the metal ion migration resistance of the copper clad laminate and strengthen the product. reliability. At present, after 106, 1080 ordinary thin glass fiber cloth is impregnated with novolac-cured high-content filler adhesive system, the appearance of the prepreg formed by oven baking is very prone to pinhole problems. The apparent pinhole defect of the prepreg is a hollow phenomenon that occurs in the void area between the warp and weft yarns of the glass fiber cloth because it is not covered by the resin. For example, when the gluing machine produces a prepreg with a resin content of 71% for ordinary 106 thin fiber cloth, the number of apparent pinholes in the prepreg is very large, and the apparent quality is obviously unqualified. There are 25 to 30 pinholes in each 300×300mm area of the prepreg. defect.

For the above pinhole problem of prepreg, it is difficult to have obvious improvement effect by adjusting the index of glue system, parameter setting of gluing machine and other conventional technological means. Therefore, the qualified rate of producing thin prepreg is greatly reduced due to the apparent quality problem, which increases the manufacturing cost of the product. The use of prepreg with apparent pinhole defects to press the board, especially for the board with a single prepreg composition structure, will affect the electrical properties and reliability of the copper clad laminate itself, which in turn will affect the electrical insulation performance of the PCB board, undoubtedly increasing the product quality. risk of quality problems. As the PCB production process continues to develop towards high-layer HDI, the demand for 106 thin prepregs is also increasing. Therefore, how to improve the apparent pinhole problem of thin prepregs containing high filler ratio adhesives to ensure product quality. It has become a practical problem that needs to be solved urgently within the scope of control.

Contents of the invention

The purpose of the present invention is to provide a production method of a thin prepreg with a high content of filler glue, which can effectively solve the apparent pinhole defect of the thin prepreg, and ensure the electrical performance and reliability of the copper clad laminate made using it.

In order to achieve the above object, the present invention provides a method for producing a thin prepreg with a high content of filler glue, comprising the following steps:

Step 1. Provide electronic-grade glass fiber flat cloth; the nominal mass per unit area of the electronic-grade glass fiber flat cloth is 15-50g/m ² , and the gap area between warp and weft yarns is 0-0.01mm ² ;

Step 2, preparing a resin glue solution with a high content of filler, wherein the percentage by weight of the filler (the percentage by weight of the total component, excluding the solvent in the total component) is 15-60%;

Step 3: impregnating the electronic-grade glass fiber flat cloth with the above-mentioned high-filler resin glue solution and baking to prepare a high-filler glue-based thin prepreg.

The resin content of the thin prepreg with high filler content is 60-80%.

The filler is one or more of aluminum hydroxide, silicon dioxide, mica powder, silicon micropowder, talcum powder, kaolin, calcium carbonate, talcum powder and the like.

The present invention provides another method for producing a thin prepreg with a high content of filler glue, which comprises the following steps:

Step 1. Provide electronic-grade glass fiber flat cloth; the nominal mass per unit area of the electronic-grade glass fiber flat cloth is 15-50g/m ² , and the gap area between warp and weft yarns is 0-0.01mm ² ;

Step 2, preparing a resin glue solution with a high content of filler, wherein the weight percentage of the filler (accounting for the weight percent of the total components, excluding solvent) is 15-60%, and the resin glue solution with a high content filler includes novolac resin curing agent;

Step 3: impregnating the electronic-grade glass fiber flat cloth with the above-mentioned resin glue with a high content of filler, and baking to prepare a thin prepreg with a high content of filler glue.

The number average molecular weight of the phenolic resin in the novolac resin curing agent is 1200-2000.

The filler is one or more of aluminum hydroxide, silicon dioxide, mica powder, silicon micropowder, talcum powder, kaolin, calcium carbonate, talcum powder and the like.

The resin content of the thin prepreg with high filler content is 60-80%.

The beneficial effect of the present invention is: the production method of the thin prepreg with high content of filler glue system of the present invention effectively solves the apparent pinhole defect of the thin prepreg, improves its qualified rate, and ensures the electrical performance and reliability of the copper clad laminate made by using it. Sex, thereby ensuring the electrical insulation performance of the PCB board and improving product quality.

Description of drawings

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so as to make the technical solutions and other beneficial effects of the present invention obvious.

In the attached picture,

Fig. 1 is the production method flowchart of the thin prepreg of high-content filler adhesive system of an embodiment of the present invention;

Fig. 2 is a flowchart of a production method of a thin prepreg with a high filler content adhesive system according to another embodiment of the present invention.

Detailed ways

A method for producing a thin prepreg with a high content of filler glue system according to an embodiment of the present invention, as shown in Figure 1, comprises the following steps:

Step 1 S1, providing electronic-grade glass fiber flat cloth; the nominal mass per unit area of the electronic-grade glass fiber flat cloth is 15-50g/m ² , and the gap area between warp and weft yarns is 0-0.01mm ² ;

Step two S2, prepare the resin glue solution of high-content filler; The formula of the resin glue solution of this high-content filler adopts prior art, comprises: resin, curing agent, accelerator, solvent and filler; Wherein the percentage by weight of filler (accounting for total The percentage by weight of the component, excluding the solvent in the total component) is 15-60%, and the filler is one of aluminum hydroxide, silicon dioxide, mica powder, silicon micropowder, talcum powder, kaolin, calcium carbonate, talcum powder, etc. One or more kinds, the resin can be epoxy resin glue, acrylate glue, polyester glue, polyurethane glue or polyimide glue.

Step 3 S3, impregnating the electronic-grade glass fiber flat cloth with the above-mentioned high-filler resin glue solution, and baking to prepare a thin prepreg with high-filler glue system. Baking conditions can be prior art. The resin content of the prepared thin prepreg with high content of filler glue is 60-80%.

Another embodiment of the present invention is a method for producing a thin prepreg with a high content of filler glue system, as shown in Figure 2, which includes the following steps:

Step 1 S1', providing electronic-grade glass fiber flat cloth; the nominal mass per unit area of the electronic-grade glass fiber flat cloth is 15-50g/m ² , and the gap area between warp and weft yarns is 0-0.01mm ² ;

Step 2 S2', preparing resin glue with high content of filler; the formula of resin glue with high content of filler adopts the prior art, including: resin, curing agent, accelerator, solvent and filler; wherein the weight percentage of filler (accounting for The percentage by weight of the total component, excluding the solvent in the total component) is 15-60%, and the filler is aluminum hydroxide, silicon dioxide, mica powder, silicon micropowder, talcum powder, kaolin, calcium carbonate, talcum powder, etc. One or more, the resin can be epoxy resin glue, acrylate glue, polyester glue, polyurethane glue or polyimide glue, and the curing agent is a novolak resin curing agent. The number average molecular weight of the phenolic resin in the phenolic resin curing agent is 1200-2000.

Step 3 S3', impregnating the electronic-grade glass fiber flat cloth with the above-mentioned high-filler resin glue solution, and baking to prepare a thin prepreg with high-filler glue system. Baking conditions can be prior art. The resin content of the prepared thin prepreg with high content of filler glue is 60-80%.

The main reasons for the pinhole problem of thin prepregs for high-filler adhesive systems: a. Since the adhesive system contains more than 15% by weight of fillers, the actual resin content after removal of fillers for prepregs with a certain resin content is relatively small. At the same time, each filler has an oil absorption value. During the dispersion process of the filler in the resin glue system, the resin needs to gradually wet and cover the surface of the filler, which leads to a smaller absolute amount of resin, so that there is not enough resin to cover the gap between the warp and weft yarns. void area. The problem of apparent pinholes in prepregs increases with decreasing resin content. b. When the glass fiber cloth is contacted and infiltrated with the resin glue system, the resin flows and forms a film to gradually fill the gap between the warp and weft yarns covering the glass cloth. However, when the film-forming ability of the resin adhesive system itself is insufficient, the prepreg will form a local surface tension gradient, and the glue tends to shrink, resulting in insufficient spreading ability to the void area of the glass cloth warp and weft yarns, resulting in uneven thickness of the resin film layer. In the square hole formed by the warp and weft yarns, the thickness of the resin film layer is thinner towards the center of the gap. When it is lower than a certain critical value, there is no resin in the gap area, that is, the "pinhole" of the prepreg is formed. "defect. In the resin glue system, novolac resin is used as the curing agent. When the number average molecular weight distribution of the resin is below 1000, the film-forming ability of the resin is poor, and the apparent quality problem of no resin filling in the gap area of the warp and weft yarns of the thin prepreg is also obviously serious. .

Comparative test of film-forming ability of novolac resins with different number-average molecular weights:

Two kinds of phenolic resins with number-average molecular weights of 800-1000 and 1200-1500 were adjusted to proper viscosity with methyl ethyl ketone solvent, and the rotational viscosity test resin viscosity was stable at about 450 centipoise. The resin was titrated on the smooth surface of polyimide (PI) release film and 18um electrolytic copper foil, and the contact angle after the resin was spread and stabilized on the medium was detected by KRUSS contact angle tester. The film-forming ability of phenolic resin was characterized by contact angle test.

Table 3. Comparison of film-forming ability of novolac resins with different number-average molecular weights

The data in Table 3 above show that the phenolic resin with a large number average molecular weight has a smaller contact angle and better film-forming ability than the phenolic resin with a small number average molecular weight.

Example 1:

Prepare ^the resin glue solution with a high content of filler, wherein the filler accounts for 20% by weight of the total component, and use 106 thin electronic-grade glass fiber flat cloth (flat and thin 106) with a warp and weft yarn void area of 0.005 to 0.008 mm to soak in high In the resin glue solution containing fillers, a thin prepreg with a resin content of 71% and a 106 high-filler glue system is baked. Compared with a prepreg made of ordinary thin 106 glass fiber cloth, the prepreg has no appearance The pinhole problem improves the qualified rate of the product. The comparison is shown in Table 4 below:

Table 4, the appearance contrast of prepreg of the present invention and existing prepreg

Example 2:

On the basis of Example 1, a novolac resin curing agent with a number average molecular weight ranging from 1200 to 2000 is used in the resin glue with a high content of filler, and 106 thin electronic grade glass fiber flat cloth (flat and thin 106) is used to infiltrate In the resin glue solution with high filler content, a thin prepreg with a resin content of 71% and a 106 high filler glue system is baked. Compared with a prepreg made of ordinary thin 106 glass fiber cloth, the prepreg has The appearance can completely avoid pinhole defects, greatly improving the pass rate of products. The comparison is shown in Table 5 below:

Table 5, the appearance contrast of prepreg of the present invention and existing prepreg

To sum up, the production method of the thin prepreg with high content of filler adhesive system of the present invention effectively solves the apparent pinhole defects of the thin prepreg, improves its qualification rate, and ensures the electrical performance and reliability of the copper clad laminate made using it. Then ensure the electrical insulation performance of the PCB board and improve product quality.

The above are only preferred embodiments of the present invention, and for those skilled in the art, various other corresponding changes and modifications can be made according to the technical solutions and technical concepts of the present invention, and all these changes and modifications All should belong to the protection scope of the claims of the present invention.

Claims (4)

1. the working method of the slim prepreg of a high levels of filler glue system is characterized in that, comprises that step is following:

Step 1, provide electronic-grade glass flat cloth; The nominal mass area ratio of the flat cloth of said electronic-grade glass is 15-50g/m ², it is 0-0.01mm through the weft yarn interval area ²

The resin adhesive liquid of step 2, preparation high levels of filler, wherein the shared total weight percentages of components of filler is 15-60%, does not comprise solvent in said total component; Said resin is the resin of epoxy resin glue system, SGA system, polyester glue system, polyurethane adhesive system or polyimide glue system;

The resin adhesive liquid of step 3, high levels of filler that the flat cloth impregnation of electronic-grade glass is above-mentioned, baking promptly makes the slim prepreg of high levels of filler glue system, and the resin content of the slim prepreg of said high levels of filler glue system is 60-80%.

2. the working method of the slim prepreg that high levels of filler glue as claimed in claim 1 is is characterized in that said filler is one or more in white lake, silicon-dioxide, mica powder, silicon powder, kaolin, lime carbonate, the talcum powder.

3. the working method of the slim prepreg of a high levels of filler glue system is characterized in that, comprises that step is following:

Step 1, provide electronic-grade glass flat cloth; The nominal mass area ratio of the flat cloth of said electronic-grade glass is 15-50g/m ², it is 0-0.01mm through the weft yarn interval area ²

The resin adhesive liquid of step 2, preparation high levels of filler, the shared total weight percentages of components of filler wherein is 15-60%, do not comprise solvent in said total component, and the resin adhesive liquid of this high levels of filler comprises the linear phenolic resin solidifying agent; The number-average molecular weight of the resol in the said linear phenolic resin solidifying agent is 1200-2000; Said resin is the resin of epoxy resin glue system, SGA system, polyester glue system, polyurethane adhesive system or polyimide glue system;

Step 3, with the resin adhesive liquid of the above-mentioned high levels of filler of the flat cloth impregnation of electronic-grade glass, baking promptly makes the slim prepreg of high levels of filler glue system, the resin content of the slim prepreg of said high levels of filler glue system is 60-80%.

4. the working method of the slim prepreg that high levels of filler glue as claimed in claim 3 is is characterized in that said filler is one or more in white lake, silicon-dioxide, mica powder, silicon powder, kaolin, lime carbonate, the talcum powder.

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